Field of the Invention
The field of the invention relates to a piezo shaker and a method for shaking a probe.
Brief Description of the Related Art
Automated analyser systems for use in clinical diagnostics and life sciences are produced by a number of companies. For example, the Stratec Biomedical AG, Birkenfeld, Germany, produces a number of devices for specimen handling and detection for use in automated analyser systems and other laboratory instrumentation.
Preparation and analysis of samples is part of everyday practice in laboratory or clinical work. Often the preparation requires mixing of several components of a sample. Mixing can be required, for instance, after a further component to a sample has been added, or in the case of particles suspended in a liquid sample.
Available solutions for mixing of samples include the use of electric motors for producing a shaking movement of a sample in a container. The electric motors comprise stepper, electronically commutated or direct current motors. Solutions using permanent or electromagnet are also known.
When using electric motors or magnets, movement patterns, such as linear or orbital movements, are often fixed or cumbersome to change and adjust. In other cases, the number of available choices is limited. Furthermore, achievable frequencies conventionally are limited towards the high-frequency ranges. Wear and friction in conventional drives for shaking probes is a further problem.
Another solution of the state of the art is presented in WO 2011/113938 A1, which discloses an agitator by vibrations including an annular resonator to which is applied a vibratory stress by piezoelectric transducers. The preferred stress shape is a bending of the ring perpendicularly to its plane in order to excite inherent modes at relatively low frequencies. The use of a solid annular transmitter enables the vibrations to be satisfactorily controlled in order to maintain satisfactory transmission to the sample to be agitated, and to focus them on it. The excitation frequencies are frequencies inherent to the ring or to the tank. The piezoelectric transducers expand and contract in order to transmit the movement to the tank comprising a sample. The movement is thus not transmitted to the platform but instead transmitted to the tank. The tank is being bent in order to mix the sample. The transduced movement is not a controlled movement but a vibrational movement.